Conventionally known is a combination metering machine, such as the one shown the cutaway side view of FIG. 30, as an apparatus in which an object of metering, such as foodstuff, is distributed to a plurality of hoppers and weighed in individual batches, a combination of the batches is selected so that the sum total of individual measured weight values is approximate to a target value, and the selected batches of the object of metering are discharged and joined, thereby obtaining a variable resembling the target value.
This apparatus comprises a circular feeder 21 provided in the central portion of the apparatus, a plurality of straight-advance feeders 22 arranged extending radially from the central portion, intermediate hoppers 23 and metering hoppers 24 arranged individually under the straight-advance feeders 22, open-close mechanisms 25 for the hoppers 23 and 24, a discharge chute 28, a collecting chute 26, and a collecting hopper 27.
When the object of metering is transported to the circular feeder 21 by means of a conveyor or the like, in this apparatus, the object of metering is radially distributed and introduced into the individual intermediate hoppers 23 by means of the straight-advance feeders 22. The respective discharge gates of the intermediate hoppers 23 open as the open-close mechanisms 25 are driven, whereby the contained object of metering is discharged to the corresponding metering hoppers 24. The metering hoppers 24 receive and weigh the object of metering discharged from the intermediate hoppers 23. The open-close mechanisms 25 are operated to open the respective discharge gates of the metering hoppers 24, thereby allowing the object of metering to be discharged through the gates, so that the quantity of the object of metering can be approximated to the target value by combining the batches of the object of metering contained in the individual metering hoppers 24. The batches of the object of metering from the metering hoppers 24 are collected in the collecting chute 26 by means of the discharge chute 28, discharged through the collecting hopper 27 to be, for example, bagged, and transported to the next stage.
The above-described combination metering machine can be used for metering a bulk material. If it is used to meter a sticky material, however, it is subject to various drawbacks such that the sticky material adheres to and remains on the inner surface of each hopper, thereby lowering the metering accuracy and processing speed, and its maintenance takes time.
To avoid this, a net is provided on the inner surface of each hopper so that the contact surface between the hopper and the object of metering is reduced to prevent the object of metering from remaining on the inner surface. In this case, however, arranging the net takes time, and the net makes it more difficult to clean the inner surface of each hopper. Therefore, the previously handled object of metering is left even after the cleaning, thus entailing insanitary conditions, and the metering accuracy is lowered.
Moreover, the net is liable to be damaged during the cleaning operation, and resulting metal pieces may possibly be entrapped.
Conventionally, furthermore, the individual hoppers are arranged circumferentially along the side face of the metering machine, a cleaner must make a round of the side portion of the metering machine as he or she cleans all the hoppers. In the conventional combination metering machine, moreover, the hoppers cannot be easily removed.
FIG. 31 is a front view showing a conventional combination metering machine in which a plurality of batches of an object of metering (work) are combined to a predetermined weight as the object is discharged.
This combination metering machine, which comprises a circular feeder 141, straight-advance feeders 142, intermediate hoppers 143, metering hoppers 144, a collecting chute 145, and a discharge hopper 146, has a circular plane configuration such that the intermediate hoppers 143 and the metering hoppers 144 are radially arranged around the circular feeder 141.
In this combination metering machine, the work is first supplied to the circular feeder 141 by means of a conveyor or the like and distributed in a radial manner. Then, a predetermined quantity of the work is introduced into each intermediate hopper 143 by means of each corresponding straight-advance feeder 142.
Subsequently, the intermediate hoppers 143 discharge and supply this predetermined quantity of the work to the metering hoppers 144 right under them. The batches of the work contained in the individual intermediate hoppers 144 are combined to set a target-value weight. Further, the metering hoppers 144 selected corresponding to the target-value weight discharge the work into the collecting chute 145. The collecting chute 145 collects the batches of the work having the target-value weight so that they get together in the discharge hopper 146.
The discharge hopper 146 opens its discharge gate at a predetermined timing, thereby allowing the work with the target-value weight to be discharged downward. The discharged work is transported to the next stage by means of a conveyor or other transportation means, whereupon it is subjected to bagging or some other process.
FIG. 32 is a side view of the discharge hopper 146. The discharge hopper 146, which is supported on the apparatus body by means of a supporting portion 147, has a discharge gate 148 at its lower portion. The discharge gate 148 is opened and closed as indicated by chain line in the drawing by means of an open-close mechanism 149.
The open-close mechanism 149 is composed of link arms 150a, 150b and 150c connected to one another. A press member 152 of a drive unit can engage the link arm 150a, and the discharge gate 148 is connected to the link arm 150c. Thus, when the press member 152 advances, the link arms 150a, 150b and 150c rock to open the discharge gate 148 as indicated by chain line in the drawing, thereby allowing the work to be discharged.
In the conventional combination metering machine constructed in this manner, however, the discharge hopper 146 is subject to the following drawbacks.
First, if the discharge hopper 146 receives a non-conforming (NG) work batch such that the target-value weight cannot be attained after the selection of a plurality of metering hoppers 144, for example, the discharge hopper 146 cannot discriminate the conformity, so that the work can be discharge only to the same position under the discharge hopper 146 at any time. Therefore, conforming work batches must be separated from non-conforming ones outside the combination metering machine, which requires much labor.
Secondly, the discharge hopper 146 is arranged so that the work is discharged by operating the discharge gate 148, so that contact sounds or noises are produced at the contact region between the discharge gate 148 and the discharge hopper 146 every time the gate is opened and closed.
Since the discharge hopper 146 itself has a tetragonal plane section and a substantially trapezoidal lateral section, moreover, its construction is complicated, and the discharge hopper 146 cannot be easily cleaned.
Furthermore, the construction of the open-close mechanism 149 for opening and closing the discharge gate 148 of the discharge hopper 146 is complicated, the components used are too many to enjoy lightweight design, the cleaning operation is not easy, and high costs are entailed.
A combination metering apparatus is used as an apparatus for efficiently collecting, for example, articles having varied weights in sets of a plurality of pieces for each prescribed weight, in the manner described above. The combination metering apparatus of this type incorporates a large number of metering machines, which each comprise a metering base and a metering container placed on the metering base. Batches of an object of metering are put individually into the respective metering containers of all the metering machines, and their respective weights are measured. Since the respective weights of the batches of the object of metering in the measured metering containers are not uniform, a plurality of batches of the object of measurement are selected among all the batches of the object of metering so that the prescribed weight of final articles of trade, e.g., bagged ones, can be obtained.
In each metering machine incorporated in this combination metering apparatus, it is natural to accurately measure the object of metering contained in its own metering container. If the object of metering contained in the metering container is selected as one of articles for bagging, it must be securely discharged in a very short time.
However, sticky materials, such as pickled vegetables, or highly watery materials adhere to the inner peripheral surface of the metering container. In this case, some of the object of metering adhering to the inner peripheral surface is left as it is without dropping even though the lower end portion of the container is opened downward. In consequence, the weight of the dropped and bagged article cannot attain the level of the prescribed weight.
Conventionally proposed as means for removing the object of metering, thus adhering to the inner peripheral surface, is a metering container which is designed so that a net is provided adjacent to the inner peripheral surface lest the object of metering directly touch the inner peripheral surface. Also proposed is a method in which a shutter is opened, and an object of metering, adhering to an inner peripheral surface inside the shutter without dropping, is separated by blowing compressed air against the inner peripheral surface.
According to the method in which the net is used, however, the object of metering adheres to the net, so that the net must be frequently washed. According to the method in which the compressed air is used, on the other hand, the object of metering is separated indirectly from the inner peripheral surface, so that all the object of metering cannot always be securely separated and dropped from the inner peripheral surface.
Further, pool hoppers and metering hoppers used in the conventional metering apparatus of this type have shapes such that it is difficult to discharge the object of metering in a short time, and a sticky object of metering, in particular, is liable to adhere to the hoppers, and the hoppers cannot be easily cleaned.